bluewave

https://news.stanford.edu/2021/01/11/climate-change-caused-one-third-historical-flood-damages/ In a new study, Stanford researchers report that intensifying precipitation contributed one-third of the financial costs of flooding in the United States over the past three decades, totaling almost $75 billion of the estimated $199 billion in flood damages from 1988 to 2017. The research, published Jan. 11 in the journal Proceedings of the National Academy of Sciences, helps to resolve a long-standing debate about the role of climate change in the rising costs of flooding and provides new insight into the financial costs of global warming overall. “The fact that extreme precipitation has been increasing and will likely increase in the future is well known, but what effect that has had on financial damages has been uncertain,” said lead author Frances Davenport, a PhD student in Earth system science at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “Our analysis allows us to isolate how much of those changes in precipitation translate to changes in the cost of flooding, both now and in the future.” The global insurance company Munich Re calls flooding “the number-one natural peril in the U.S.”However, although flooding is one of the most common, widespread and costly natural hazards, whether climate change has contributed to the rising financial costs of flooding – and if so, how much – has been a topic of debate, including in the most recent climate change assessments from the U.S. government and the Intergovernmental Panel on Climate Change. At the crux of that debate is the question of whether or not the increasing trend in the cost of flooding in the U.S. has been driven primarily by socioeconomic factors like population growth, housing development and increasing property values. Most previous research has focused either on very detailed case studies (for example, of individual disasters or long-term changes in individual states) or on correlations between precipitation and flood damages for the U.S. overall. In an effort to close this gap, the researchers started with higher resolution climate and socioeconomic data. They then applied advanced methods from economics to quantify the relationship between historical precipitation variations and historical flooding costs, along with methods from statistics and climate science to evaluate the impact of changes in precipitation on total flooding costs. Together, these analyses revealed that climate change has contributed substantially to the growing cost of flooding in the U.S., and that exceeding the levels of global warming agreed upon in the United Nations Paris Agreement is very likely to lead to greater intensification of the kinds of extreme precipitation events that have been most costly and devastating in recent decades. “Previous studies have analyzed pieces of this puzzle, but this is the first study to combine rigorous economic analysis of the historical relationships between climate and flooding costs with really careful extreme event analyses in both historical observations and global climate models, across the whole United States,” said senior author and climate scientist Noah Diffenbaugh, the Kara J Foundation Professor at Stanford Earth. “By bringing all those pieces together, this framework provides a novel quantification not only of how much historical changes in precipitation have contributed to the costs of flooding, but also how greenhouse gases influence the kinds of precipitation events that cause the most damaging flooding events,” Diffenbaugh added. The researchers liken isolating the role of changing precipitation to other questions of cause and effect, such as determining how much an increase in minimum wage will affect local employment, or how many wins an individual player contributes to the overall success of a basketball team. In this case, the research team started by developing an economic model based on observed precipitation and monthly reports of flood damage, controlling for other factors that might affect flooding costs like increases in home values. They then calculated the change in extreme precipitation in each state over the study period. Finally, they used the model to calculate what the economic damages would have been if those changes in extreme precipitation had not occurred. “This counterfactual analysis is similar to computing how many games the Los Angeles Lakers would have won, with and without the addition of LeBron James, holding all other players constant,” said study co-author and economist Marshall Burke, an associate professor of Earth system science. Applying this framework, the research team found that – when totaled across all the individual states – changes in precipitation accounted for 36 percent of the actual flooding costs that occurred in the U.S. from 1988 to 2017. The effect of changing precipitation was primarily driven by increases in extreme precipitation, which have been responsible for the largest share of flooding costs historically. “What we find is that, even in states where the long-term mean precipitation hasn’t changed, in most cases the wettest events have intensified, increasing the financial damages relative to what would have occurred without the changes in precipitation,” said Davenport, who received a Stanford Interdisciplinary Graduate Fellowship in 2020. The researchers emphasize that, by providing a new quantification of the scale of the financial costs of climate change, their findings have implications beyond flooding in the U.S. “Accurately and comprehensively tallying the past and future costs of climate change is key to making good policy decisions,” said Burke. “This work shows that past climate change has already cost the U.S. economy billions of dollars, just due to flood damages alone.” The authors envision their approach being applied to different natural hazards, to climate impacts in different sectors of the economy and to other regions of the globe to help understand the costs and benefits of climate adaptation and mitigation actions. “That these results are as robust and definitive as they are really advances our understanding of the role of historical precipitation changes in the financial costs of flooding,” Diffenbaugh said. “But, more broadly, the framework that we developed provides an objective basis for estimating what it will cost to adapt to continued climate change and the economic value of avoiding higher levels of global warming in the future.”

This is the composite for the last 10 La Niña events to reach 6” or more in NYC during January and February. That’s why we need that -PNA trough out West to pull back off the West Coast at storm time. Like I said in the post above, relevant details like that may not be known for a while yet. And there may have probably been lesser than 6” storms that had more leeway.

I will be happy If we can get that -PNA trough off the West Coast for at least a few days. The 360 hr EPS is taking a step in the right direction. But you can see how important that ridge over the Plains was for the 3-22-18 event when the -PNA trough pulled back.

I think we’ll need that -PNA trough over the Western US to back off a bit from what the week 2 EPS has. In March 2018 it pulled just off the West Coast with higher heights over Southern Canada. This allowed a ridge in Minnesota for separation between systems.

The fact that NYC is yet to drop below 20° highlights how little Arctic air has been around. This is only the 5 year that NYC has gone this far into the cold season without one. For Boston it’s only the 6th year not to drop below 16. At BTV it’s only the 10th year not to reach 0 yet. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 1975-01-12 26 0 2 2013-01-12 22 0 3 2021-01-12 20 1 - 2002-01-12 20 0 - 1932-01-12 20 0 Time Series Summary for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2002-01-12 22 0 2 2007-01-12 20 0 3 1975-01-12 17 0 4 2021-01-12 16 1 - 1955-01-12 16 0 - 1929-01-12 16 1 Time Series Summary for Burlington Area, VT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2007-01-12 5 0 2 2002-01-12 3 0 3 2016-01-12 2 0 - 2000-01-12 2 0 5 2021-01-12 1 1 - 2012-01-12 1 0 - 1987-01-12 1 0 - 1955-01-12 1 0 - 1932-01-12 1 0 - 1924-01-12 1 0

I wonder if the ridge bridge over the top of the -PNA trough today is a result of the EPS seeing continuing influence from the SSW? This raises the question of whether the EPS will correct from what it’s showing now in early February. We really need a strong -EPO -AO connection to counteract the influence of the -PNA.

The latest EPS weeklies keep the window of opportunity open from January 25th to Feb 1st. Jan 11-18 Jan 18-25 Jan 25-Feb 1 Feb 1 - Feb 8

It’s as if the historic December 2015 +13.3 reset the whole winter climate warmer. NYC Dec 15....+13.3 Jan 16....+1.9 Feb 16....+2.4 Dec 16....+0.8 Jan 17....+5.4 Feb 17....+6.3 Dec 17....-2.5 Jan 18.....-0.8 Feb 18....+6.7 Dec 18....+2.6 Jan 19....-0.1 Feb 19....+0.9 Dec 19....+0.8 Jan 20....+6.5 Feb 20....+4.8 Dec 20.....+1.7 Jan 21.....+3.6...so far

It’s ironic that we may get our first -EPO drop since mid-December as the PNA is turning negative just after the 20th. This can often happen as the ridge pulls back to Aleutians and higher heights extend toward Alaska. So it looks like the PNA drop which the models had originally forecast near the start of February is moving up by 6-10 days.

You area has been warm rather than mild. POU is +5.1 through the 10th. The departures are being driven by the warm minimums. POU is +2.3 for the average daily max departure and a whopping +7.8 for the minimums. NYC is +3.6 with a +2.7 max and a +4.5 min departure. BTV is even more extreme at +6.8. They are +2.9 on the max and a +10.7 on the minimum. The more impressive warm departures have been the further north you go.

The Pacific Jet continues on steroids. Looks like a 220KT max today. So no surprise that we will continue with this mild airmass.

It’s always a challenge guessing when snowfall will start up again following a long break. It will be a month this week since the area near the coast saw accumulating snows. Snowfall return intervals after past pauses have been highly variable.

The all or nothing snowfall pattern continues for North America. Rollercoaster ride hitting record highs in October followed by record lows in November. Quick rise in mid-December then a fall around Christmas. Now the snow extent is near the bottom of the list for January 9th.

You have to look at it through the lens of the pattern that we have at the time. When we have a record breaking Pacific Jet pattern, we need all the help that we can get from Pacific blocking. So in the case this December, it took the poleward extension of the ridge through the EPO region to the North Pole to get us the snowstorm. But during other years with a less amped up Pacific Jet, we have gotten by with just the +PNA and +EPO and -AO. That’s why the +EPO during El Niño’s can be OK. The North Pacific Jet weakens while the STJ becomes the strongest. This helps carve out the trough over the SE US and allows the 50/50 low and high over New England hold its ground with a +EPO and weaker Pacific Jet. So +EPO during an El Niño isn’t the liability it can be with a La Niña. That’s why our best La Niña seasons like 95-96 had such frequent blocking near Alaska. While great El Niño’s had the STJ running the show with -AO and +PNA. NYC 2 greatest snowstorms 27.5”....Jan 22-23 -16 super El Niño +EPO 2016 01 20 43.26 2016 01 21 31.89 2016 01 22 48.24 2016 01 23 71.40 2016 01 24 71.56 2016 01 25 14.98 2016 01 26 29.36 2016 01 27 55.70 2016 01 28 160.56 2016 01 29 177.26 26.9”.....Feb 11-12-06....La Niña -EPO 2006 02 09 -53.06 2006 02 10 -93.77 2006 02 11 -74.28 2006 02 12 -35.51 2006 02 13 -69.84 2006 02 14 -214.72 2006 02 15 -288.49 2006 02 16 -309.34 2006 02 17 -330.28 2006 02 18 -298.10 Late November 95 into April 96 historic snowfall pattern for a La Niña

The only -EPO drop of the whole winter so far was a few days before the the snowstorm. So the +PNA and -AO couldn’t get the job done without the -EPO assist. This was when the strong block popped up over the pole. ftp://ftp.cdc.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt 2020 12 01 57.33 2020 12 02 -20.52 2020 12 03 1.92 2020 12 04 -3.55 2020 12 05 18.98 2020 12 06 113.53 2020 12 07 160.49 2020 12 08 91.29 2020 12 09 24.46 2020 12 10 -40.49 2020 12 11 -98.53 2020 12 12 -90.08 2020 12 13 -32.48 2020 12 14 -11.99 2020 12 15 48.80 2020 12 16 122.15 2020 12 17 153.25 2020 12 18 199.37 2020 12 19 250.26 2020 12 20 239.82 2020 12 21 120.24 2020 12 22 70.85 2020 12 23 58.12 2020 12 24 69.31 2020 12 25 92.27 2020 12 26 68.14 2020 12 27 3.10 2020 12 28 -1.63 2020 12 29 11.33 2020 12 30 61.32 2020 12 31 60.59 2021 01 01 127.22 2021 01 02 264.17 2021 01 03 296.05 2021 01 04 248.51 2021 01 05 260.79 2021 01 06 249.45 2021 01 07 137.72

The cold 13-14 and 14-15 winters seem like a long time ago. It’s like the super El Niño in 15-16 hit the warm reset button. We knew something extreme was going on when December 2015 went +13.3.

This repeating model error has been so frequent in recent years, that the Upper Plains is one of the few spots on the planet that will see a slight decline in the new 30 year climate normals. Time after time, the coldest temperature departures have been dropping to our west. I guess the Pacific Jet is just too difficult for the models to handle long range.

It looks like the coldest temperatures by later in the month will drop to our west again. Notice how much weaker the Pacific blocking is along the West Coast of North America than originally forecast. The extreme Pacific Jet that brought record low pressure to the Aleutians just won’t relax. New run Old run

At least this -NAO is paying off for parts of Europe. Much easier to put together a record snowfall when an unfavorable Pacific can’t impact your pattern. Shows how just a -NAO can be a big influence for Europe. The AEMET weather agency described the situation as "exceptional and most likely historic". Earlier in the day, children in Madrid could be seen hurling snowballs or playing under snow-covered palm trees, while others snapped photos of the rare whiteout which began in earnest the day after Spain celebrated King's Day -- or Epiphany.

Models are correcting more positive with the EPO for later in the month. This is telling us that the models continue to underestimate the strength of the Pacific Jet. That’s why the EPS are warmer than the GEFS during week 2.

That firehose Pacific Jet won’t be denied. The combo of that Jet and the south based block is suppressing the southern stream. So all the precip is PAC NW and SE.

NYC generally needs a cold winter to get more than 1 event of 10” or more in a single season. The last time this happened was during the cold winters of 13-14, 10-11, 09-10, and 03-04. But one of these days, NYC will eventually get 2 events in a mild winter. https://www.weather.gov/media/okx/Climate/CentralPark/sixplussnow.pdf 12-17-20...10.5 1-24-16.....27.5 2-13-14....12.5 1-22-14....11.5 2-8-13......11.4 1-26-11.....19.0 12-26-10....20.0 2-25-10.....20.9 2-10-10......10.0 12-20-09.....10.9 2-12-06......26.9 1-22-05.......13.8 1-28-04.......10.3 12-5-03.........14.0 2-17-03.......19.8 12-30-00......12.0

We may need a loop like March 1888. Ideally, it would occur a little further east than in 1888. While we have less Arctic air now, the SSTs and moisture content would be higher. So lower ratio with more total liquid equivalent. https://www.wunderground.com/blog/weatherhistorian/the-great-blizzard-of-1888-americas-greatest-snow-disaster.html

I still think that we have a chance to see a 40-50” snowstorm event somewhere between NYC and Boston in the coming years.

And this may help to compensate for #2 also. But I know that there are extended snow cover fans out there that may not feel that way. I am more about snowstorm intensity and quality than how long it remains on the ground. https://www.sciencedaily.com/releases/2019/01/190124115353.htm Even though climate change is expected to reduce the total amount of U.S. snowfall this century, it's unlikely to significantly rein in the most powerful nor'easters that pummel the East Coast, new research indicates.